Histories: Scars of a catastrophe

By Richard Lovett

Fifteen thousand years ago, a vast lake sprawled through the valleys of what is now western Montana. Known as Lake Missoula, it was created when a lobe of ice moving south from Canada blocked the Clark Fork river, which drains much of the region. Then, one day, the ice dam broke. Water roared down the canyons at 100 kilometres an hour – 2000 cubic kilometres of it spilling onto the plains of eastern Washington in a few days. There it leapt river channels and scoured new paths across the intervening ridges. When the water receded, it left behind a mystery that geologist J Harlen Bretz was determined to uncover. In doing so, he challenged the foundations of an entire science.

Geologist J Harlen Bretz found himself in eastern Washington by accident. It was the summer of 1922 and he and a group of students from the University of Chicago were planning to study the glaciers of the North Cascades, a chain of mountains further to the west. They never reached their destination. “For some reason the trip was cancelled and they wound up with two or three weeks to spare,” says local historian John Soennichsen, who has researched Bretz’s story.

Borrowing a car from a friend, Bretz set out with his students to explore a region called the scablands, where the rich soil of Washington’s wheat country is interrupted by great gashes carved into dark, basaltic rock. Bretz was captivated by this strangely scarred landscape. “The scablands”, he wrote later, “are wounds only partially healed – great wounds in the epidermis of soil with which Nature protects the …

To continue reading this premium article, subscribe for unlimited access.